Degeneration of the human Betz cell due to amyotrophic lateral sclerosis

The giant pyramidal cell of Betz is known to be partially affected in cases of amyotrophic lateral sclerosis (ALS). Though biochemical, physiologic, and histologic properties of the diseased Betz soma have been investigated, the morphologic status of the largest portion of cell membrane, that of its vast dendritic array, has not. Precentral cortex from six patients, ages 51 to 64 years, who had succumbed to the sequelae of ALS was examined using variants of the Golgi techniques. ALS is shown to be a degenerative disorder which causes a decline in the integrity of the Betz dendritic arbor as well as of the soma of origin. Dendritic fragmentation occurs and numerous irregularities appear, while the number of dendritic spines declines. Concomitantly, a reactive gliosis encroaches upon the soma and may extend onto initial dendritic segments. These observations are remarkably similar to those of the Betz cell in normal aging. The correlation of qualitative histologic data in these conditions is meaningful in light of suggestions that aging and ALS may be related processes. This could provide some clue as to the etiology of Betz cell degeneration and of motor neuron disease.